ST_Srid-PolarDB(PolarDB)-阿里云帮助中心

Returns the spatial reference identifier (SRID) of a spatial object.

SRID identifies the coordinate reference system assigned to a geometry. Verifying the SRID before running spatial operations — such as coordinate transformation — prevents mismatched coordinate system errors.

Syntax

int4 ST_Srid(meshgeom geom);
int4 ST_Srid(sfmesh sfmeshObject);

Parameters

Parameter	Type	Description
`geom`	meshgeom	The meshgeom object to query.
`sfmeshObject`	sfmesh	The sfmesh object to query.

Return value

Returns an int4 value representing the SRID of the input object.

Example

The following example retrieves the SRID of a meshgeom object created with SRID 4490:

SELECT ST_Srid(
  ST_MeshGeomFromText(
    'Srid=4490;MESHGEOM(PATCH(INDEXSURFACE(VERTEX(0 0 2,0 10 3,10 10 1,10 0 1),INDEX((0,1,2),(1,2,3)))))'
  )
);

Result:

---------
    4490

What's next

To create a meshgeom object from WKT input, use ST_MeshGeomFromText.